An electrical device for a switching or control unit is described in German Patent No. DE 33 10 477 A1. This electrical device is used inside a motor vehicle, for example, as a control unit for an injection system and has a housing for accommodating a circuit carrier in the form of a circuit board. The electrical contacting of the electrical device takes place via a connection area of the housing, which is situated on a front side of the housing. For this purpose, a front side of the housing is closed with the aid of a plug body, which is typically designed as a plastic injection-molded part. Connecting pins and/or connecting lugs protrude through the plug body, which may be electrically contacted on the one hand with the circuit carrier inside the housing and on the other hand with a vehicle-side wiring harness plug, referred to hereafter as a connecting plug. The plug pins are situated inside a typically rectangular, circumferential, and closed wall area of the plug body (plug collar). To contact the electrical device with the connecting plug, the connecting plug encompasses the wall area (plug collar) of the plug body on its outer circumference, centering of the connecting plug on the circumferential wall area of the plug body taking place due to corresponding geometric dimensioning of the connecting plug, so that the electrical contacting of the connecting pins with corresponding counter elements in the connecting plug takes place without problems. To additionally connect or lock the connecting plug to the electrical device in a mechanically fixed way, the known electrical device has multiple latches in the area of its plug body outside the wall area, which interact with a corresponding counter contour on the connecting plug. Furthermore, the connecting plug has a closure lever, for example, which interacts with the latches and, in its locking position, produces a clamped or force-fit connection of the connecting plug to the electrical device.
A connection arrangement between an electrical device and a (vehicle-side) connection and/or wiring harness plug, in which a fixing or locking element (latch on the plug body) situated outside the circumferential wall area of the receiving contour on the electrical device and used with the connecting plug, is also referred to as an outer lock. An outer lock enables in particular relatively good leak-tightness between the receiving contour and the connecting plug, which makes the penetration of moisture, etc., more difficult or prevents it, since the connecting plug encompasses the receiving contour and/or the wall area from the outside. It is disadvantageous that the connection arrangement inevitably has a relatively large width due to the connecting plug situated outside the circumferential wall area and the closure mechanism thereof. This is problematic in particular in the case of cramped installation conditions in motor vehicles, in which, for example, the height of the electrical device has to be selected to be as small as possible. For this reason, connection arrangements between an electrical device and a connecting plug are also known from the related art, in which the fixing or locking elements are situated inside the receiving contour and/or the circumferential wall area of the connecting plug. The (vehicle-side) connecting plug is situated in this case inside the receiving contour of the plug body, so that particularly low electrical devices may be produced with regard to a housing height of the electrical device (and/or the width of the receiving contour). It may be disadvantageous that such an arrangement of the fixing or locking elements and the connecting plug, which form a so-called inner lock, do not achieve the leak-tightness of an outer lock with respect to the leak-tightness. However, there are applications in which an inner lock is used either due to cramped installation conditions, or due to leak-tightness requirements not being required. In summary, conventional connection arrangements are designed either to form an outer lock or an inner lock, whereby the fixing or locking elements are situated for this purpose either outside the receiving contour or inside the receiving contour of the connection area on the electrical device.